Means for utilizing brake torque in a vehicle suspension



Aug. 29, 1950 A. s. PAGE 2,520,777

- MEANS FOR UTILIZING BRAKE TORQUE IN A VEHICLE SUSPENSION Filed April22, 1948 4 Sheets-Sheet 1 O O "E 1?;

2| 23 'i f T3 Z INVENTOR. O O 0. C) Q ANCEL s PAGE ATTORNEY Aug. 29,1950 A. 5. PAGE 2,520,777

MEANS FOR UTILIZING BRAKE TORQUE IN A VEHICLE SUSPENSION 4 Sheets-Sheet2 Filed April 22, 1948 Ill,

IN V EN TOR.

.Q FQ .ANCEL" 5 PAGE ATTORNEY A. s. PAGE 2,520,777 7 MEANS FOR UTILIZINGBRAKE TORQUE 4 Sheets-Sheet 3 Aug. 29, 1950 IN A VEHICLE SUSPENSIONFiled April 22, 1948 INVENTOR.

PAGE

@@ ANICEI. s

ATTORNEY I Aug. 29, 1950- 2,520,777

- A. 5. PAGE MEANS FOR UTILIZING BRAKE TORQUE IN A VEHICLE SUSPENSIONFiled April 22, IL 9 48 4 Sheets-Sheet 4 INVEN TOR. AN C E L S PAG E I 0a Q ATTORNEY Patented Aug. 29, 1950 MEANS FOR UTILIZING BRAKE TORQUE INA VEHICLE SUSPENSION Ancel S. Page, Portland, Oreg.

Application April 22, 1948, Serial No. 22,661

This invention relates to the type of dual axle vehicle suspension inwhich a pair of axles are located at the respective ends of a pair ofpivotally-mounted, longitudinally-extending walking beams or walkingbeam assemblies mounted at each side of the vehicle for up and downpivotal movement with respect to the main frame of the vehicle. Eachwalking beam may consist of a solid or rigid pivotally-mounted beam, or,as is more customary, may comprise a leaf spring, or a pair of leafsprings, formed into a'longitudinally-extending, pivotally mounted leafvspring assembly.

When the wheel axles are located at the respective ends of suchpivotally mounted walking beams a difficulty arises with the applicationof the brakes to the wheels, for example, if the vehicle is travelingrapidly on a highway and, in particular, if the vehicle is travelingdown an appreciable grade. Ihe problem presented, which has long beenrecognized and for which, to the best of my knowledge, no adequatesolution has previously been found, is caused by the fact that a greaterforce, or load or braking torque, is imposed on the front axle wheelsthan on the rear axle wheels. Manifestation of this condition canreadily be observed. Thus when equal braking force is applied to frontand rear wheels, the rear wheels can often be seen to lock and dragalong the road surface while the front wheels continue to revolve, thusindicating the heavier load on the front wheels.

To prevent this undesirable skidding of the rear wheels, with consequentexcessive wear of the rear tires, it has become more or less customaryto adjust the brakes so that less braking force will be applied to therear wheels than to the front wheels. However, no definite adjustment ofthe brakes solves the difliculty inasmuch as such variable factors asamount of load, vehicle momentum, and road grade, are involved in eachcase.

A further manifestation of the problem involved may be observed from thefact that the front ends of the walking beams, when the brakes areapplied to the wheels, will exhibit a tendency to bear down furtherwhile the rear ends will correspondingly show a tendency to be liftedslightly, thus also giving evidence of increased load or forceencountered by the front wheels with the opposite condition beingencountered by the rear wheels.

The problem above outlined has been recognized as a particularly seriousone in the use of the familiar types of dual axle logging trucks 6Claims. (01. 280-1045) and trailers, for these vehicles haul heavy loadsnot only along highways but down relatively steep mountain roads andslopes where prolonged application of the brakes is necessary.

During my experience with the operation of logging vehicles under suchcircumstances over a number of years, I have tried in various ways tocope with and to relieve this unequal load or force imposed at differentends of the walking beam assembly. Finally it occurred to me that thebraking torque developed under such conditions and which was imposedupon, and was required to be absorbed by, the front wheels, axlehousings and corresponding ends of the walking beams, could, if properlyutilized, aid in relieving the additional load thrust on the forwardwheels. Experiments which I then performed in developing this idearesulted in the present invention.

7 The principal object of the present invention accordingly is toprovide an improved vehicle suspension in which walking beams, or theirequivalent, are included, and in which the added load thrust on theforward wheels and. axles resulting from the application of the brakes,can be in parttransferred to the rear wheels.

Another object. of my invention is to provide a dual-axle-walking-beamconstruction in which excessive brake torque can be transmitted to thewalkin beams in a novel manner and thence transmitted through thewalking beams for a definite purpose.

A further and more specific object of my invention is to provide animproved construction involving vehicle axles and walking beams in whichthe brake torque, which has heretofore been required tobe absorbed bythe axle mountings and ends of the walking beams, can be advantageouslyutilized in counter-balancing the unequal distribution of weight on thefront and rear axles.

An additional related object of this invention is to provide asemi-flexible mounting for the axles in the walking beams, in place ofthe customary rigid axle mounting, which will permit some'slight degreeof turning of the axles with respect to the ends of the walking beams towhich they are attached, as a means of enabling the brake torque on theaxles to be utilized instead of being merely dissipated.

A still further object of the present invention is to provide animproved vehicle suspension capable of carrying out the above objects,which will be simple and practical and capable of installation on anyvehicle inwhich walking beams or their equivalent are used.

These objects and other advantages I have been able to attain bydispensing with the customary welded or rigid axle mountings or housingsat the ends of the walking beams and by providing special mountings towhich brake torque arms have been added and which act to transmitbraking torque from the axles to the walking esteema; definite riijnher'and' finally by utilizing the 'brak'ing torque and resulting forcesadvantageously as hereinafter briefly de scribed with reference to theaccompanying drawings.

In the drawings: w 2" Fig. l is a side elevation of a dual axle loggingI trailer embodying one form of my inventionithe near side Wheels havingbeen-omitted from the drawing for the sake of clarityarid' a portion ofone of the mountings for the axles being-shown in section; A

fFiEuZ'lS an end-elevation of the same vehicle, theyviewbeing-taken fromthe right of Fig. l; s

Figs-3 is a; fragmentary; vertical sectioncorresponding to line 3- 3 ofFig; 1,: but drawn to a much larger scale,- and including also a portionofthe 'brake'drum for the adjacentwheel; v s t Fig. 4 isafragmentaryverticalsection online 44 of 1, drawn to; a' larger scale, with portionsof the aXle-mounting'sleeves broken away; Fig, ,5 is a fragmentaryvertical section on line 5+5of Fig. 1,butdrawn to a larger scale; -rFig.6 is "an exploded view, in perspective, of the various membersconstituting the axle mounting at the'end of-one of the walking beams,including-also the specialtorque arm connection, with the-axle andwalking beam entirely omitted from the drawing,the members being shownarrangedjn their related order;

- Fig. 7-is adiag-rammatic representation of the operation of myinvention when employed in a dual axle logging trailer traveling in ahorizontal line;

Fig. 8 is asimilar diagrammatic representation of the-roperationof myinvention in such a vee hicle when traveling down a grade; and

9 ;isa diagrammatic representation ,of a slightly modified form ofconstruction involving my invention. r

Referring first to Figs. 1 and 2, -the. dual; axle logging trailerinwhich I have illustrated. my invention as being employed, includes ajmain frame I ll, pivotally supported on a'central transverse trunnionshaft l l by means ofinner supports ll and outside brackets IS. \Aswivelly mounted bunk I4 is supported on top of the frame and in turnsupports the log load in the usual manner. yThe trailer is adapted. tobe connected to a leading truck (not shown) by means of the usualreachI5- A pair of spring walking beams I 6 are clamped at 'theiricenters onsaddles H which are rockably mounted on :the trunnion shaft ll ateach-side of; the vehicle in the usual manner. The two axles- -I8 and [9are mounted at the respective ends of the walking beams but instead ofbeing rigidly mounted-in any of the customary 'ways, are mounted by aspecial mounting hereinafter to be explained.

An axle housing, comprising an upper section 20-and a lower section 2|-(shown more clearly in Fig. 6), the two sections being secured togetherby bolts; extending through the pairs of abutting flanges 22 and 23, iscarried at each end of the spring walking: beams IS. The upper sectionabout the axle H8 or iii within the housing sections 26 and 2!. The twoflanges 28 of the rub- "berbusliirig'ext'ehdover the sides of thehousmg-"sections 2E] and 21 when the housing is secured about the axle,as shown in Figs. 3 and 5.

The interior bearing faces of the housing sections 28 and 2 may be madecylindrical but I prefer to -have them in the form of a shallow annulartrough, as illustrated a1r29 in Fig. 5, and correspondingly formtheouter bearing surface of the rubber-bushing 2'! with aflatt'endafinular" ridge 3%). Thus I make'the'rubber bushing thickest around itscesarean-the result'that a slight tipping'of the axlein'ither direction(for example 'a tipping 'of' the axle 18in Fig. 5) will cause the top ofthe axle to be "brought more nearly into parallelism with one portion ofthe hbus'iiig bearihg'surfacewhile the bottom of the axle'is broughtmore nearly into parallelism with channel 24 to accommodate the reducedend of the pppositeportion of thehousing bearing sur face.

"A flanged sleevetl (Figs. 2, 3, 5 and 6) formed in two half sectionswhich are bolted together, as 'shov'vn in Figs.'2 and 6, which'sleevehas an annular flange 32,15 placed around the axle adjacent thehousing 20, 2| on'the'iriner side. A second ange" sleeve 33' '(Figs.'3,' 5, and 6), also formed in": two 'half' secticns' which are boltedtogether, 'and"having' an inner flange and an outer flange'36,"is"'placed-around the axle adjab'ent the housingf2l l, 2i ontheouter side. Clamping'bolts'35 (Fief'3) extend through the flanges 32'andarer these sleeves and thus cause thesesl'e'eves to hold the housing20, Hand the fla ges'i'28 of the rubber bushing 21 clamped tigtl'y'b'e'tw'een the sleeves as shown in Fig. 3.

n inwardly curved arm 37, which Idesi'g'nate as brake torque arm (Fig.4-. and 6), is formed integral with onesection of thefiangetli of the31s was. This torque arm 31 terminates in a horiiontal'bearing 38. Arubber bushing (not shown) is placed inthis bearing 38 and a pin35"'(Fig."4) extends through the bushing and through'a pair'of alinedholes in the pair of arms 46 which extend down from the lower half of abracket clamp 4 I 42 (Figs 1, 4 and 6), which bracket is clamped aboutthe spring walking beam l6." The; ends of the 'pinare peened, orsuitable other provision is made to keep the pin from slippingout ofplace. A reinforcing web 45 connects the arms 49 'above the location ofthebearing- 38. r 'Fach of theaxles l8 and |9 is formed in the customarymanner -with an integral annular flange43 (Figs. 3, 4 and 5); near eachend having brake shoe anchors to which anarm 44 from each brake shoe ishingedly connected. The outer flange 360:? the sleeve 33 is bolted tothe adjacent integral axle flange- 43. Thus the sleeve 33 and with itthe sleeve 3| are secured in this way to the axle while the housing 20,2!, for the end of thess-pring'walking beam I6, is clamped between thetwo s'lee'vesr'without, however, being rigidly secured to the axle. Dueto theresiliencygof the rubber bushing 21 the housing 20, 2| and theaxle location of the bracket clamps 4|, 42.

I. can rotate slightly with respect to each other without the occurrenceof any frictional movement of the inner face of the bushing on' the axleor the outer surface of the bushing in the housing.

I have described the manner in which one end of one axle is mounted onone end of one of the spring walking beams Hi. The mounting for theaxles at the other three ends of the walking beams is similar, as willbe apparent from Figs. 1 and 2 and thus need not be separatelydescribed.

It will be apparent from the description thus far that when the brakesare applied to the Wheels, causing the brake shoes on each wheel to bepressed against the brake drum of the wheel, the customary resultingbrake torque received by the axle from the brake shoe anchor on the axleflange 43, will be transmitted to the torque arms 31. Furthermore, anytendency of an axle to turn as the result of the brake torque will not,as heretofore, be resisted to any extent by the axle housing. The braketorque, transmitted to the torque arms 3'! will result inan upward or adownward force being exerted at the ends of the torque arms, dependingupon the direction of rotation of the associated wheels. But since theends of the torque arms are attached to the brackets 4|, 42 which areclamped about the spring walking beams, the brake torque is transferredinto forces exerted either upwardly or downwardly on the spring walkingbeams at the The effect of such forces and the manner in which theseforces operate to cause the principal objects of my invention to beattained can be explained more simply and clearly with reference tothediagrammatic Figures '7 and 8 of the drawings.

Referring first to Fig. 7, the dual axle logging trailerdiagrammatically represented is assumed to be traveling on a level roadtowards the right and thus in the direction indicated by the arrow D.All four wheels as viewed in this figure will be rotating in clockwisedirection. The weight of the vehicle load L will exert a vertical forcedownward, which is indicated by the broken line A, and this line willpass through the longitudinal center of the walking beams l6 causing theweight to be distributed equally on both axles I 8 and I 9. Thus all thewheels can be said to have approximately equal traction. Now, let it beassumed that the brakes are suddenly applied to the wheels in an effortto stop the travel of the vehicle quickly. It will be clear that aresultant force, depending upon the momentum of the load, will bedirected obliquely downwardly and forwardly, for example in some suchdirection as indicated by the broken line B. This would cause the load Lto tip downwardly and forwardly if the load were free to do so; butsince the load is not free to move in this manner, this force isdirected first against the forward sections of the walking beams l6producing an extra load thrust on the forward axle I 9 and on theforward wheels and causing a tendency of the front ends of thewalkingbeams to be lowered. and the rear ends of the walking beams to beraised. In fact, if the walking beams were sufiiciently rigid and ifthis force were sufficiently great, the rear wheels could even be liftedmomentarily from the ground. Also the application of the brakes to thewheels causes brake torque to be exerted on the axles in the directionof the rotation of the wheels. With the old customary axle mountings, inwhichthe axles are rigidly secured to housings, which in turn arerigidly secured to the ends of the walking beams, the brake torque willexert a force tending to rotate the axle housings in the same directionand this in turn will exert a tendency to twist the front ends of thewalking beams down still lower while exerting the opposite tendency onthe rear ends of the walking beams. Thus the tendency for greater weightto be imposed on the forward wheels and corresponding less weight to beimposed on the rear wheels will be increased by the braking torque. Theresult of the combined tendencies and forces is to increase the tractionof the front wheels and reduce the traction of the rear wheels.Obviously, under such conditions, if the brake application is equal forall wheels, the rear wheels, due to their reduced traction, may ceaserotating entirely and merely skid along the road surface. This is acommon occurrence and may frequently be observed in vehicles of standardtypes in which walking beams form part of the vehicle suspension.

However, in my invention, instead of the rigid mounting of the axles inthe housings at the ends of the walking beams, and absorption of thebrake torque by the axle housings and the ends of the walking beams, thebrake torque is transferred to the torque arms 3'! and 31' which in turntransfer this torque into an upward or downward forcethrough the bracketclamps to the walking beams at the points where the bracket clamps areattached. Thus, as indicated in Fig. '7, the brake torque from the frontwheels becomes an upwardly directed force acting upon the walking beamsbetween the front ends and the central mounting on the trunnion shaftII. The momentary effect of this upward force tending to move theforward portions of the walking beams upwardly, which tendency isincreased by the reverse tendency of the rear torque arms 31 to lowerthe rear sections of the walking beams, would be to shift the downwardload center weight line A rearwardly to some such position as indicatedby the broken line C. But if the load center line of the weight is inthe position of the line C instead of the line A, the resultant downwardforward force thrust would be along the broken line F instead of alongthe line B, the line F being parallel to the line B but located to therear of the line B. This force line F crosses the walking beams nearerthe center points II and thus there will be less difference between theamounts of resultant load thrust on the forward and rear axles. In otherwords, there would be less differential in the traction'of the front andrear wheels.

A similar condition is set up when the vehicle is traveling down gradeand brake torque is encountered. In Fig. 8 the same vehicle isdiagrammatically represented as traveling down a grade in the directionof the arrow D. The vertical load center line A no longer crosses thewalking beams l6 at their longitudinal center but crosses them furtherforward, thus indicating that there is a greater load on the front axleand wheels even without any application of the brakes. The resultantdownward forward force line when brakes are applied, thus the line B,will in this case be still further forward than as indicated,

in Fig. 7.

With the application of the brakes the brake torque, with my invention,nevertheless operates in a manner similar to that previously explainedwith reference to Fig. 7. Thus the forward torque arms 31, as indicatedin Fig. 8, will deliver an upward thrust on the forward sections of thewalking beams l6 and the rear torque arms 31' will exert a downward pullon the rear sections of aw y 7 these walking "Ehis tendencytorotate' thewalliing beamsin counter-clockwise direction will havea;n--e'fle t,similar =-to-that already 1 d escribed-with reference-toFig. 7 t movingthe effective: vertical load center line backinto some such-position asindicated by the line-C in 8. The resultant downward iorce line B willbe moved-bacleinto some such position'as indicated hymns-broken line-F.; 'This resultant forceline F in- Fig. 8" crosses thewalking beamsatsome distanceforward from the longitudinalcenter poi-nts,'-thusindicating that-there wills-till be the: greater lead on the frontwheels than on therear.- whee1s, but sinee tllis point of intersectionoi the forcelineF-withthe walking beams is notas far forward as the lineB; the-(inferential intheloaglscarried by Pthe forward and rear Wheelswill be decidedly less than would be the case if my invention were notemployed-and thus the operation of the torque arms increases thetraction of the rearwheelsin each case;

I VlFhi-le -mydelineation of the theoretical forces involved in theoperation ptmy invention may not be complete, and while the forcefactors may be more complicatedthan I haverepresented them to-be,nevertheless the fact remains th at' with 'my invention the rear -wheels will have greater tractiom-and extensive tests which Ihaver madeinthe hauling of log loads under similar conditions, both with andwithout theemployment of my invention, have proved this factconclusively.

While in the various drawings thus far I have illustrated the walkingbeams-asbeing located above the axles my 1 invention is not necessarilyto' be limited tosueh arrangement. In Fige a: vehicle with thewalkingbeams extending below the axles is'diagrammatieally shown; Itwillbe apparent that the torque arms will-- operate in the same way-toexert an'upwardlydireeted force on the forward sections of -the walkingbeams and the opposite tendency on -the rear sections ofthe:wa-lkingbeams.- Various modifications could alsoibe-made-1n =the'constructionofthe various palrtsofmytehicle suspension-within the scopeoPmyinveiition. The particular "construe tion which I have ill-ilstratedanddescribed is similar to' -thavwhichl have actually used in practice; TiHowever;iit-is notmy intention to 1mm my invention otherwise than "assetforth-in the claims;

I claim:

1. In a vehicle suspension, a loair of walking bealiiassemblies,axles-located at the respective ends of I said walking beam assemblies,means for attaching'said axlesto said ends'of said-walk ing beamassemb1ies;.-b rake elements for the" ve: hiclewheels located nearthe-'ends-of said axles, means for anchoring 'saidbrake' elements "inplace, means for permitting slight limited relative rotation 'of saidaide attaching means with respect to said-anchoring means, torquetranse, fer-ring; members connected with said anchoring meansarid means"connecting said torque t'rans ferring members with 'saidwalking beamassem blies respectively atspaced distances in from the respective endsof said walking beam assemblies; whereby brake torque imposed-by saidbrake elements'on said anchoring means will be received by saidtorquetransferring members and utilized bys'said transferring -members toexert-upward or-downwardthrusts on said walkingbearnassemblies'toaccomplish the purpose described, v

2. In a vehicle suspension, a pair of walking beam; assemblies, axlemounted atthe respective place; iiieans' forpe'r assemblies 8 ends ofsaid walking beam assemblies, housings for'sa'id axles atta hd' to'theends of saidfx'valk ins beam assemblies: brakef'eremefits for we've I rting'slightlimited relative rotaneno'f said the housings with respect tosaid; anonenn'g means; torque arms"connected with said anchorin means;and means coimect-v ing s'aiderque arms" with said Walkingb'eiims'pe'ctiveiy" at spaced distances in from the respectiveenss ofsaid"wa1king beai'n aJSSrrilflliesIWlieTebYbrake torque imposed by saidbrake elements onsaid anchoring means will be receivci'by said-torque"arms and utnizlib said arms'to' exertupward ordownware thrus n saia'lklflg team memes-es to I accomplish-thepurpose described.

beam asse lilie ax es "mounted at the res ew hi clesusiiefision," a pairof "walking eie neatsrsethevehicle honsingsfor' permitting} slightlimited relative rbt'atioiitof. aid axle v tnrespect to said nousings,brake elementsfor j the vehicle "wh'eels' "lo-' cat'ed'near th dsofsaid'aides; means secured to eacn endj'f said axles" for anchoringsaid brake elements members; connected with said anchoring meansrespectively and means; connecting said torque transferrin members is;th "said walking} beam assemblieswesp etively at spa'c'ed"" t"fi'bnitherespet ite ends ofsaid' walking beam assemblies, "t'vherbyfbralke torque nnposed bfi' said brakefeiefiiefits'; orI said anchoringmeans will be received by said f terquej transferring manners" andutilized by said tran'sferring memhei s to 'e'x'ertup or dewfiward"thrusts on sseffibli'es to accomplishthe purpose described. r 4.} I aven'i'me suffififls I011, 'a, pair of walking t the'respeetive ends ofih'gs" for said" axles at =walliingbeam's; brake Heels located near thewidest" saidaxie'sj a gesecrrreq "to end of said'akhs'for authoring saidbrakeelements' in'pi'ace; means 'forpenfiittin slightlimitd relativerotation bffsaid" aXle housings with respect to, said anchoring'hafige'ttifque' armgconneetd withfsaid' flanges respectively," and means confleeting saidto'r'quearms with *said winkin beams respectively ate"spaceddistahce from the respective endsofsaid walking be'ama'whereonsaid flanges aria? axles will be received by said torquarms'andTiitiliiz'd by said arms to exertiu wa'rd r'dovv wa'rd' thrustson saidwalkmg eams to accbiiibl'ish' the purpose escribes;

5 A;vehicleisusgieiision"including"a pair of walking beam assemblies;axles mountedat'the respective ends'of said walkingbeam assemblies;ousing for said xles attached to" thee lds" of said walkingbeamasseinbnes, means within said housings for permitting Slight limited"relative rotation" of said axleswitn respect to said housings; brakeelements? r the" vehicle wheels located' near theends' of said aXles aflange secured to each end" of" said axles for anchoring said'br'akeelementsin =p1ace torque transferrin mem ers connected wthsaid.fflangesiespectively and means connect n said-torque transferringmembers with'said walking beam assemblies respeetively atspaceddistafieesin from the respective ends of said walking beam assemblies,whereby brake torque imposed by said brake elements on said flanges andaxles will be received by said torque transferring members and utilizedby said transferring members to exert upward or downward thrusts on saidwalking beam assemblies to accomplish the purpose described.

6. A vehicle suspension comprising a pair of walking beams, axlesmounted at the respective ends of said walking beams, housings for saidaxles attached to the ends of said walking beams, resilient bushingswithin said housings for permitting slight limited relative rotation ofsaid axles with respect to said housings, brake elements for the vehiclewheels located near the ends of said axles, a flange secured to each endof said axles for anchoring said brake elements in. place, torque armsconnected with said flanges respectively. and means connecting saitorque arms with said walking beams respective at a spaced distance infrom the respective en of said walking beams, whereby brake torq"imposed by said brake elements on said flanges and axles will bereceived by said torque arms and utilized by said arms to exert upwarthrusts on said walking beams to purpose described.

- ANGEL S. PAGE.

REFERENCES cITEn The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date Marcum Nov. 7, 1933 Number

